JPH07178950A - Thermal printer - Google Patents

Abstract

PURPOSE:To make printing with a uniform density regardless of a printing ratio by controlling a drive energy (a current-working time) of a heating resistor correspondingly to the number of resistors to be driven among heating resistors provided on a thermal head. CONSTITUTION:A heating energy of a heating resistor of a thermal head 154 is controlled by a strobe signal issued from Port 4 - Port 7 of a CPU 70. In other words, heating resistors to be driven are specified in accordance with printing data DATA 1 and DATA 2. On a strobe signal applied after the transmission of the printing data, the heating resistors are driven so as to generate a required energy. a thermistor 422 is provided for detecting a temperature of the thermal head 154.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer for printing by applying drive pulses to a plurality of heating resistors arranged in a thermal head to generate heat.

[0002]

2. Description of the Related Art Conventionally, a voltage is applied to a heating resistor,
2. Description of the Related Art A thermal printer is known in which a color-developing layer on the surface of a thermal paper is colored by the generated energy to perform printing. In this type of printer, it is known that the print density changes depending on the strength of the generated energy.

[0003]

Generally, a plurality of heating resistors are arranged in the thermal head. If you focus on a specific heating resistor, it will be driven (generates heat)
When the number of resistors is large (the printing rate is high), the heat generated by the surrounding heat generating resistors affects the heat, and the heat is generated in excess of the heat amount originally generated by the heat generating resistors. There is a problem that the print density becomes high. Also,
When the number of driven heat generating resistors is small (when the printing rate is low), the heat of the driven heat generating resistors is diffused or absorbed by surrounding members, and a predetermined amount of heat cannot be obtained. .

[0004]

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a thermal printer which can always obtain a uniform print density regardless of the printing rate.

Therefore, in the present invention, a plurality of heating resistors, driving means for driving the plurality of heating resistors, and detection for detecting the number of the plurality of heating resistors driven for printing. And a control unit that controls the drive unit so as to change the energy generated when the plurality of heat generating resistors are driven, based on the detection result of the detection unit. In addition, the drive means,
A configuration having a voltage applying unit that is driven by applying a predetermined voltage to the plurality of heating resistors, and the control unit having a time changing unit that changes a time interval in which the voltage applying unit applies the voltage; can do. Further, the time changing means can set the time interval so as to be substantially proportional to the number of driven heating resistors.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A thermal line printer which is an embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, the thermal line printer 10 has a thermal line head 154, which will be described later, on a sheet P of A5 size thermal paper based on print information from a personal computer (not shown). An image can be formed (print operation) at high speed by using the line print mechanism 60, and the line print mechanism 60 is configured so as to be compatible with, for example, a portable personal computer, that is, small enough to be portable. .

This thermal line printer 10 is shown in FIG.
It is configured so that the use in the horizontal state as shown in FIG. 2 and the use in the vertical state as shown in FIG. 2 can be selected. Further, the thermal line thermal line printer 10 is configured such that the thermal line printing mechanism 60 is driven by a rechargeable nickel-cadmium battery 64 housed in a battery chamber 62 described later. In this embodiment, the thermal line print mechanism 60 is also configured so that it can be driven by a DC voltage obtained by converting an AC power source using an AC / DC converter (not shown). Here, when the DC voltage is not applied and the drive is not performed, the above-mentioned nickel-
The cadmium battery 64 is set to be charged.

Specifically, this thermal line printer 1
Reference numeral 0 includes a housing 12 having a substantially rectangular parallelepiped shape, and the housing 12 includes an upper housing portion 14 and a lower housing portion 16. The upper housing portion 14 and the lower housing 16 are detachably fixed to each other by screws (not shown).

Here, in the substantially central portion of the front portion of the upper housing portion 14 which constitutes the upper half of the housing 12, the nickel-containing nickel alloy described below extends over the upper surface 14a and the front surface 14b thereof.
A battery lid 18 that covers the battery chamber 62 that houses the cadmium battery 64 is detachably attached. Further, behind the upper surface 14a of the upper housing portion 14, the paper P is inserted into the housing 12 in a vertically long state when used in a horizontally placed state as shown in FIG. A first sheet insertion groove 20 is formed. Further, a paper discharge groove 22 for discharging the printed paper P from the inside of the housing 12 is formed in substantially the central portion of the upper surface 14 a of the upper housing portion 14 over substantially the entire width direction. Further, on the rear surface 14c of the upper housing portion 14, as shown in FIG. 2, the second sheet insertion in which the sheet P is inserted in the vertically long state when used in the vertically placed state over substantially the entire width direction. Groove 2
4 are formed. Here, the rear surface 14c of the upper housing 14 in FIG. 1 showing the horizontally placed state constitutes the upper surface of the upper housing 14 in FIG. 2 showing the vertically placed state. The first and second sheet insertion grooves 20 and 24 and the sheet ejection groove 22 have a length suitable for inserting the A5 size sheet P in a vertically long state, that is, the length of the short side of the A5 size. Each of them is formed to have a length slightly longer than that.

A power button 26 is attached to the front right side of the upper surface 14a of the upper housing portion 14 so as to be freely pushed. By pushing and driving the power button 26, a power switch 28 described later (see FIG. 3). Is turned on, and the drive system 88 and the thermal line print mechanism 60 are turned on.
Is configured to be in a drivable state. When the power switch 28 is turned on, a power (POW / CHRG) lamp 30 arranged on the front left side of the upper surface 14a of the upper housing portion 14 is turned on. Here, the power lamp 30 has a battery chamber 62.
It is set to blink when the remaining amount of the nickel-cadmium battery 64 housed therein is less than a predetermined amount.

On the other hand, on the left side of the upper surface 14a of the upper housing portion 14, an online (ONLINE) button 32, a mode setting (MODE) button 34, and a forced feed (FEED) button 36.
Are juxtaposed. Here, each time the online button 32 is pushed and driven, an online switch (not shown) is sequentially switched between an online (connected) state and an offline (disconnected) state. The online lamp 38 disposed on the front left side of the upper surface 14a of the upper housing portion 14 is set to be turned on when the online state is set and turned off when the offline state is set. ing.

Further, the mode setting button 34 is operated by pressing the button to select whether the font changeover switch (not shown) selects Mincho typeface or Gothic typeface as a character font used for printing operation. It is set to be switched sequentially. The font (Gothic) lamp 40 arranged on the front left side of the upper surface 14a of the upper housing portion 14 is turned on when the Gothic font is selected and is turned off when the Mincho font is selected. It is set.

Further, the forced feed button 36 is turned on by a drive switch (not shown) only while it is being pushed and driven, and a feed roller 84 is provided in a drive system 88 described later.
Also, the platen roller 86 is forcibly rotationally driven so that the paper P can be forcibly conveyed (discharged). Further, on the front left side of the upper surface 14a of the upper housing portion 14, a paper-less display (P.E.) lamp 42 is provided, which is turned on when the paper P is discharged from the paper transport path described later, First and second sheet insertion grooves 20, 24
Is set to blink at the same time when an abnormal state in which the paper P is inserted occurs. The four types of lamps 30, 38, 40 and 42 are each composed of an LED (Light Emitting Device) in this embodiment.

On the other hand, a recess 44 is formed on the upper surface 14a and the right side surface 14d of the upper housing portion 14 from the rear of the center of the right portion.
A release lever 46 for releasing a pressure contact state between a thermal line head 154 and a platen roller 86, which will be described later, is provided therein so as to be swingable around an axis extending along the longitudinal direction of the housing 12. . The release lever 46 is in the state shown in FIG.
1 to allow the press contact between 54 and the platen roller 86.
By swinging clockwise from the state shown in FIG. 2, the thermal line head 154 and the platen roller 86
It is set so that the pressure contact state with and is forcibly released, and the paper P sandwiched between the two can be easily taken out.

Further, as shown in FIGS. 1 and 2, the upper housing portion 14 has an upper surface 14a at substantially the center of the rear portion thereof.
Also, a back cover 48 is swingably supported on the rear surface 14c. By swinging the back cover 48 upward, the rear central portion (that is, the installation space SP in which the slide press member 192 described later is installed) in the housing 12 is opened. By thus opening the substantially central portion of the rear portion of the housing 12, the slide press for bringing the sheet P inserted from the first sheet insertion groove 20 into contact with the feed roller 84 in the horizontally placed state. The member 192 can be attached to and detached from (replaced with) the housing 12.

Here, as shown in FIG. 1, the housing 12
The right side surface 16a of the lower housing portion 16 that constitutes the lower half
A connector 50 for online connection to an external device (not shown) such as a personal computer
However, power supply connectors 52 for connecting to an AC / DC converter (not shown) are provided in the rear part. Further, as shown in FIG. 2, a density adjusting dial 54 for adjusting the print density is disposed on the left side surface 16b of the lower housing portion 16 so as to be rotatable around a vertical axis in a horizontally placed state. By appropriately rotating the density adjustment dial 54, it is possible to adjust the heat generation amount of the thermal line head 154 described later and set the print density on the paper P to a desired density.

As shown in FIG. 2, on the upper surface 14a of the upper housing 14 located on both sides of the back cover 48, there are insertion holes 58 into which both ends of the U-shaped paper guide 56 are inserted. Has been formed. As shown in FIG. 1, this paper guide 56 is used by inserting it into the insertion hole 58 in a horizontal state, and is formed on the bottom surface of the lower housing portion 16 in a vertical state shown in FIG. It is stored and held in a holding groove (not shown).

Next, the structure of the thermal line printing mechanism 60 arranged in the housing 12 will be described in detail with reference to the drawings starting from FIG. 3 is a top view showing the internal structure of the housing 12 with the battery lid 18 removed and the upper housing portion 14 removed, and FIG. 4 shows a cross section taken along the line AA in FIG. As shown in FIGS. 3 and 4, a battery chamber 62 is disposed in the front center of the housing 12, and the battery lid 18 is opened in the battery chamber 62. Thus, the nickel-cadmium battery 64 is exchangeably loaded. On the right side of the battery chamber 62 in the drawing, a power switch 28 that is turned on / off by the power button 26 described above is provided.

The positional relationship between the power button 26 and the power switch 28 is clear from FIG. 4, and the actuator 28a of the power switch 28 is in a state of being laterally offset from the central axis of the power button 26. Has been done. This offset is set in order to use the upper surface of the switch body 28b of the power switch 28 as the lower receiving surface of the spring 66 for constantly urging the power button 26 upward.

The power switch 28 is fixed on the control board 68 as shown in FIG. The control board 68 is fixedly mounted on the bottom surface of the lower housing portion 16 of the housing 12 via a screw (not shown). Here, on the control board 68, the connection connector 50 described above is provided.
And the power supply connector 52 is fixed. In addition, on the control board 68, a microcomputer 70 that controls the overall control, an EPROM 72 in which a control program, initial values, etc. are stored,
For example, D for expanding print information on a bitmap
RAM 74, a first font ROM 76 in which Gothic fonts are stored, and a second font in which Mincho type fonts are stored.
The font ROM 78 and the like are attached. A pair of coil springs 182 for urging a head support 156 described later upward to press the thermal line head 154 supported by the head support 156 against the platen roller 86 penetrates through the control board 68. Is formed with a pair of openings 80.

Here, as shown in FIGS. 3 and 4, on the left side of the battery chamber 62 in the drawing, the above-mentioned four LEDs 30, 3 are provided.
An LED board 82 on which 8, 40 and 42 are mounted is attached. On the other hand, behind the battery chamber 62, a feed roller 84 and a platen roller 86 are rotatably supported, and the feed roller 84 and the platen roller 86 are also rotatably supported.
A frame 90 to which a drive system 88 for rotating and driving is attached is provided. The frame 90 is fixed to the lower surface of the upper housing portion 14 from below via three screws 92 (shown in FIGS. 3 and 11) in this embodiment.

As shown in FIGS. 6 to 10, the frame 90 is a substantially flat frame body integrally formed with three mounting bosses 94a, 94b, 94c into which the above-mentioned screws 92 are respectively inserted. 96 and this frame body 9
The left side plate 98 is formed integrally with the left end portion of the frame 6 in an upright state, and the right side plate 100 is formed integrally with the right end portion of the frame body 96 in the upright state. . Here, the frame main body 96 guides the paper P inserted from the first or second paper insertion groove 20 or 24 between the frame main body 96 and an under guide 184 (described later) disposed below the frame main body 96. Common paper feed path F for feeding
It specifies 0. Further, the left side plate 98 functions as a mounting board for a drive system 88 described later, and the left and right side plates 9 are
The reference numerals 8 and 100 function as a base for rotatably supporting the head support 156.

On the other hand, as shown in FIG. 6, the frame body 96
A discharge guide portion 104 for guiding the paper P, for which the printing operation has been completed, to the paper discharge groove 22 in a state in which a space 102 for housing and disposing the platen roller 86 is provided in front of the both side plates. It is integrally provided in a state of being bridged between 98 and 100. This discharge guide section 104
As shown in FIGS. 9 and 10, is formed to have an arc-shaped cross section so as to face the outer periphery of the platen roller 86, and the end of the arc-shaped paper discharge path Fd defined between the two is the paper discharge. It opens to the groove 22.

As shown in FIG. 10, the frame body 9
The rear portion 96a of 6 is gently bent upward. On the other hand, immediately behind the frame main body 96, a substantially L-shaped insertion guide portion 106 is integrally provided in a state of being bridged between the side plates 98 and 100. As shown in FIG. 11, the insertion guide portion 106 is inserted between the gently bent rear portion 96a of the frame main body 96 and the sheet inserted from the first sheet insertion groove 20 in a horizontal state. P
Between the vertical guide 106a for defining the first paper feed path F1 for guiding the sheet toward the common paper feed path F0 and the under guide 184, and the second paper insertion groove 24 in the vertically placed state. It is integrally formed with the lateral portion 106b that defines the second paper feed path F2 for guiding the paper P inserted from the above to the above-described common paper feed path F0. Here, the base end portion of the first paper feed path F1 is opened to the above-mentioned first paper insertion groove 20, and the second paper feed path F1 is opened.
The base end of 2 is opened to the above-mentioned second paper insertion groove 24.

Here, the above-mentioned feed roller 84 is
In this embodiment, the paper P inserted into the housing 12 through the first paper insertion groove 20 when used in the horizontal state shown in FIG. To the second sheet (in detail, toward the rolling contact portion between the platen roller 86 and the thermal line head 154, which will be described later), and when used in the vertically placed state shown in FIG. The sheet P inserted into the housing 12 via the insertion groove 24 is further forwarded to the common sheet conveyance path F.
It is provided as a common transport means for transporting toward 0.

Further, as shown in FIG. 3 again, the platen roller 86 is rotatably supported in front of the frame main body 96 in a state of being positioned in the space 102 described above.
As shown in FIG. 12, the platen roller 86 includes a shaft portion 108 and a roller body 110 coaxially attached to the outer periphery of the shaft portion 108 except for both ends 108a and 108b. The roller body 110 is made of urethane foam in this embodiment.

Here, both end portions 108 of the shaft portion 108 are
Bearings 112 and 114 are fitted in a and 108b, respectively. Then, the one end portion 10 of the shaft portion 108
One of the bearings 112 fitted in the 8a has a first through hole 11 formed in a substantially central portion of the left side plate 98 shown in FIG.
Therefore, the shaft portion 108 is rotatably supported by the left side plate 98 at the one end portion 108a. The end edge of the one end portion 108a of the shaft portion 108 is
The first driven gear 118 that constitutes the drive system 88 is coaxially and integrally attached to the protruding end, which further projects outward from the one bearing 112.

Further, the other end portion 108b of the shaft portion 108
The other bearing 114, which is fitted to the right end of the right side plate 100 shown in FIG. 8, is prevented from being displaced downward in a snap coupling state in an arcuate recess 120 formed so as to open downward. The shaft portion 108 is connected to the right side plate 1 at the other end portion 108b in this manner.
It will be rotatably supported at 00.

On the other hand, as shown in FIG. 6, an opening 124 for accommodating the roller main body 122 of the feed roller 84 is formed in the rear center of the frame main body 96. Then, as shown in FIG.
A feed roller 84 is rotatably mounted on the rear portion. The feed roller 84 is provided with a shaft portion 126 as shown in FIG. 13, and the length of the shaft portion 126 is one end portion 126 as shown in FIG.
The a is projected outward from the left side plate 98, and the other end 126b is set so as to pass through the above-mentioned opening 124 and terminate at a position extending by a predetermined length therefrom. And
Since the roller body 122 described above is housed in the opening 124, it is coaxially and integrally attached to the shaft portion 126 near the other end 126b.

Here, one end portion 1 of the shaft portion 126
Although not shown, a bearing is fitted into 26a. Here, the bearing fitted in the one end portion 126a penetrates into the second through hole 128 formed in the rear portion of the left side plate 98 shown in FIG.
One end 126a of 26 is rotatably supported by the left side plate 98. In addition, one end portion 126a of the shaft portion 126
The end edge of is protruded further outward from this bearing, and the second driven gear 130 constituting the drive system 88 is coaxially and integrally attached to this protruding end.

Further, the other end portion 126b of the shaft portion 126
Are rotatably supported by bearings 132 arranged on the frame body 96 adjacent to the openings 124.
In this way, the feed roller 84 is attached to and supported by the frame 90 so as to be rotatable around the fixed axis.

Next, the structure of the drive system 88 for rotationally driving the feed roller 84 and the platen roller 86 described above will be described. First, as shown in FIG. 7, the left side plate 98 of the frame 90 serving as a substrate to which the drive system 88 is attached has a substantially square front portion 98a positioned in front.
And an upper end surface that is flush with the upper end surface of the front portion 98,
It is integrally formed with a rear portion 98b formed behind the front portion 98a in a shape substantially corresponding to the right side plate 100. On the inner surface of the front portion 98a, as shown in FIGS.
As shown in FIG. 3, a state in which the holding portion 136 that holds the drive motor 134 (shown in FIG. 3) as a so-called stepping motor that is driven by a pulse signal and that constitutes the drive system 88 protrudes inward. Are formed integrally.
A third through hole 138 into which the motor shaft 134a of the drive motor 134 is loosely fitted is formed in the front portion 98a. As shown in FIG. 3, a drive gear 140 is coaxially and integrally attached to the tip of the motor shaft 134a.

As shown in FIG. 7, the first to third support pins 142, 14 are provided at predetermined positions on the outer surface of the left side plate 98.
4, 146 are planted, and first to third idle gears 148, 150, 152, which will be described later, are rotatably attached to the first to third support pins 142, 144, 146, respectively. It is supported.

Now, referring to FIG. 14, this drive system 8
8, the configuration of a gear train as a drive force transmission mechanism for transmitting the drive force of the drive motor 134 to the platen roller 86 and the feed roller 84 will be described. The large diameter portion 148a of the first idle gear 148, which is rotatably supported by the above-mentioned first support pin 142, is the drive gear 14
The small diameter portion 148b of the first idle gear 148 meshes with the large diameter portion 150a of the second idle gear 150 rotatably supported by the second support pin 144. . The small diameter portion 150b of the second idle gear 150 meshes with the first driven gear 118 that is coaxially fixed to the platen roller 86.

On the other hand, the first driven gear 118 is the third driven gear 118.
Is engaged with a third idle gear 152 that is rotatably supported by a support pin 146 of the second idle gear 152. The third idle gear 152 is a second idle gear that is coaxially fixed to the feed roller 84.
Of the driven gear 130. Here, the number of teeth of the first driven gear 118 is set to be slightly smaller than the number of teeth of the second driven gear 130. As a result, the driving force of the drive motor 134 is transmitted through the gear train configured as described above to the platen roller 86 and the feed roller 8.
4 is transmitted to drive them in rotation. Here, during this driving, the rotation speed of the platen roller 86 is set to be slightly higher than the rotation speed of the feed roller 84. Therefore, the rear end of the preceding paper P and the front end of the succeeding paper P are reliably separated in the transport direction during continuous feeding of the paper P described later. Further, the paper P conveyed to the platen roller 86 by the feed roller 84 is taut between the both while being tensioned. In addition, between the shaft portion 126 of the feed roller 84 and the second driven gear 130,
Although not shown, a slip clutch is provided.

A head support 156 for supporting the thermal line head 154 is pivotally supported on the rear portion of the frame 90 below the frame 90 to which the drive system 88 thus constructed is attached. Due to this swinging support, the left and right side plates 98, 10 that form the frame 90
As shown in FIGS. 7 and 8, shaft support pins 158 and 160 are formed in the rear portion of the outer surface of No. 0 so as to project outward, respectively. On the other hand, the head support 156 is shown in FIG.
As shown in a state of being taken out in FIG. 2, a substantially flat plate-shaped support body 162, a left side plate 164 integrally formed on the left end portion of the support body 162 in a standing state, and a right end portion of the support body 162. A right side plate 166 integrally formed in an upright state, and a discharge guide part that is integrally formed in a front end portion of the support body 162 in an upright state and is bent with a front end inclined forward. 168 is roughly provided and configured.

Here, at the rear end portions of the left and right side plates 164, 166, support openings 170, 172 are fitted to the above-mentioned shaft support pins 158, 160 from the outside to be rockably supported, respectively.
Are formed. In addition, a pair of left and right bearings 112 and 114 for pivotally supporting the platen roller 86 are fitted and supported on the upper end surfaces of the front portions of the left and right side plates 164 and 166, respectively. Are formed. On the other hand, the support main body 162 is formed with a pair of head mounting holes 178 (only one head mounting hole is shown in FIG. 12) formed of long grooves extending along the conveyance direction of the paper P. There is.

Incidentally, a pair of left and right positioning recesses 174, 17
The width of the sheet P along the conveyance direction of the sheet P is set to an optimum value so that the corresponding bearings 112 and 114 can be fitted tightly. Therefore, in this one embodiment, FIG.
5 and FIG. 16, the bearings 112 and 114 attached to both ends of the platen roller 86 are fitted into the positioning recesses 174 and 176 of the head support 156, respectively. The relative position between the two will be accurately defined.

The head support 15 constructed in this way
A well-known thermal line head 154 is placed on the support body 162 of No. 6, and the above-mentioned head mounting hole 17
The thermal line head 154 is fixed on the support main body 162 by a pair of mounting screws (not shown) inserted from below via 8. At the time of this fixing operation, a heating jig of the thermal line head 154 (a line indicated by a symbol X in FIG. 3) is accurately positioned at a rolling contact position with the platen roller 86 via a mounting jig (not shown). The mounting position is fixed in a state where the mounting position is accurately adjusted and regulated along the conveyance direction of the paper P. In addition, this thermal line head 154
In the mounting position adjusting operation of the head support 156 to the head support 156 via the mounting jig, and the fixing operation after the position adjusting operation, the head support 156 moves the frame 90.
It is set to be executed in a state where it is removed from.

The head support 156 is constructed in this way, and the thermal line head 154 is attached / fixed to the head support 156 via an attachment jig in a state where its attachment position is accurately specified. Further, the bearings 112 and 114 attached to both ends of the platen roller 86 are fitted into the positioning recesses 174 and 176 of the head support 156, respectively, so that the relative position between the head support 156 and the platen roller 86 is increased. Is accurately specified, the head support 156 to which the thermal line head 154 is attached and fixed is swingably attached to the frame 90.
4,176 to the bearing 112 of the platen roller 86,
By inserting 114 respectively, the positional relationship between the thermal line head 154 and the platen roller 86 is accurately defined such that the heat generation position X of the thermal line head 154 is brought into precise contact with the platen roller 86. Become.

As described above, in this embodiment, since the heat generation position X of the thermal line head 154 is accurately defined so as to accurately contact the platen roller 86, the diameter of the platen roller 86 is set small. Since the diameter of the platen roller 86 has a great influence on the overall size of the thermal line printer 10, the overall configuration of the thermal line printer 10 can be miniaturized in this manner. You can do it.

On the other hand, this head support 156 is shown in FIG.
As shown in FIG. 7, a pair of spring receiving seats 180 formed on the bottom portion of the lower housing portion 16 are provided with coil springs 182 that receive the lower ends of the spring receiving seats 180.
In other words, the thermal line head 154 is rotationally biased so as to be in rolling contact with the platen roller 86 from below.
Here, as shown in FIG. 17 and FIG. 5 described above, these spring receiving seats 180 are formed through an opening 80 formed in a control board 68 disposed above the bottom portion of the lower housing portion 16. It is taken out above the control board 68.

Here, as described above, the head support 156 is swingably supported by the frame 90 to which the platen roller 86 is attached while being positioned. Therefore, the pair of coil springs 182 described above
Due to the urging force of the platen roller 86, the heat generation position X of the thermal line head 154 is surely extended over its entire length.
The state of being transferred to will be achieved. As a result, in this embodiment, at the time of printing operation, the paper P
In the state in which this is sandwiched between the thermal line head 154 and the platen roller 86, the thermal line head 154 is securely brought into close contact with the thermal line head 154 over the entire length in the width direction. Thus, in this embodiment, the paper P
The state in which line printing is reliably performed over the entire length in the width direction is achieved.

Further, in this embodiment, as is apparent from the above description, it is sufficient that the thermal line head 154 is brought into contact with the platen roller 86 at least in a rolling contact state from below. As a result, the thermal line head 154 is connected to the platen roller 86.
The urging force of the coil spring 182 for contacting with the coil 182 requires a relatively small force. Therefore, in this embodiment, the pressure contact force of the thermal line head 154 contacting the platen roller 86 is extremely small.

Thus, according to this embodiment,
The tip of the paper P nipped by the rolling contact portion between the thermal line head 154 and the platen roller 86 is engaged with the surface of the thermal line head 154 by a strong pressure contact force, and there is substantially no risk of damaging the surface. Become. Further, even if the thermal line head 154 is always in rolling contact with the platen roller 86, there is no possibility that the platen roller 86 is adversely affected by permanent deformation or the like. As a result, for example, the thermal line head 154 is separated from the platen roller 86 in the standby state, and the thermal line head is brought into pressure contact with the platen roller after the leading edge of the paper passes between the thermal line head and the platen roller. It is not necessary to provide the conventional auto-retraction mechanism configured as above. In this way, the auto-retraction mechanism that has been conventionally required is not necessary in this embodiment, and the cost can be reduced by that amount, and the size of the entire apparatus can be reduced by the amount that does not need to be provided. You will be able to do it.

It should be noted that, as shown in FIG. 19, the discharge guide portion 168 constituting the above-mentioned head support 156 is located below the platen roller 86 and in front of the platen roller 86 when the thermal line head 154 is in rolling contact with the platen roller 86. Positioned so as to face each other, the leading end of the paper P printed by the thermal line head 154 is
It is set so as to come into contact with the paper discharge guide portion 168, change its conveying direction upward, and be guided to the above-described paper discharge path Fd.

On the other hand, the frame 90 and the head support 15
As shown in FIG. 11, between the thermal line head 154 and the thermal line head 154, the common paper feed path F0 and the second
Under guide 18 that defines the bottom of the paper transport path F2
4 is installed. As shown in the bottom view of the attached state in FIG. 18, the under guide 184 has a guide body 186 on a substantially flat plate, an opening 188 formed substantially rearward of a central portion of the guide body 186, and a guide body 18.
6 and a biasing plate 190 that is taken out above the guide body 186 through the opening 188. Here, as shown in FIG. 19, the biasing plate 190 forcibly rolls the leading end of the paper P brought to the common paper feed path F0 to the feed roller 84,
By the frictional engagement force between the paper P and the feed roller 84, the paper P can be conveyed toward the rolling contact portion between the platen roller 86 and the thermal line head 154 as the feed roller 84 rotates. .

When the thermal line printer 10 is used vertically as shown in FIG.
Since the paper feed path F2 and the common paper feed path F0 are substantially in a straight line, the leading end of the paper P inserted into the housing 12 through the second paper insertion groove 24 is urged by the weight of the paper P. , And is brought down to the common paper feed path F0 by descending the second paper feed path F2, where it is surely brought to the rolling contact portion between the urging plate 190 and the feed roller 84. Therefore, in this embodiment, the urging plate 190 is
No mechanism for applying a conveying force to the sheet P is provided upstream of the rolling contact portion between the feed roller 84 and the feed roller 84 in the sheet conveying direction.

On the other hand, when the thermal line printer 10 is used in a horizontal position as shown in FIG. 1, the first paper feed path F1 and the common paper feed path F0 have a predetermined obtuse angle (in other words, a predetermined obtuse angle). Since the first sheet conveying path F1 and the second sheet conveying path 2 are set to intersect each other at a predetermined acute angle, the sheet P inserted into the housing 12 through the first sheet inserting groove 20. As it is, the leading end of the sheet is difficult to be conveyed to the common sheet conveying path F0. Therefore, in this embodiment, a conveying force is applied to the sheet P introduced into the first sheet conveying path F1 to forcibly force the common sheet conveying path F1.
In order to make it move toward 0, the first paper feed path F1
2 is a slide press member 192 as a pressure contact means for frictionally engaging the paper P on the feed roller 84 in FIG.
0 and FIG. 24, the feed roller 84 and the back cover 4
8 is arranged in the arrangement space SP defined between the feed roller 84 and the feed roller 84 so as to face the central portion of the feed roller 84. Incidentally, this arrangement space SP communicates with the first sheet conveying path F1.

This slide press member 192 is shown in FIG.
As shown in FIG. 22, the feed roller 8 is arranged so as to be movable in the horizontal direction as shown in FIG.
A surface of the press main body 194 facing the surface 4 is set to be an inclined surface inclined by a predetermined angle with respect to the horizontal line as the moving axis when the thermal line printer 10 is in the horizontal position shown in FIG. This press body 19
4. A rubber plate 196 as a friction plate, which is entirely attached to the slope of No. 4, and a coil spring 198 for pressing the press body 194 against the feed roller 84.
And is configured. Here, this press body 1
In order to allow 94 to move only along the horizontal direction in the state shown in FIG. 20 (that is, to support the feed roller 84 so that it can move back and forth only along one direction), both sides of the press body 194 are provided. In the state shown in FIG. 20, grooves 194a, 194b extending along one direction are formed, while in the center of the rear portion of the frame 90, as shown in FIGS.
As shown in FIGS. 24A and 24B, the pair of slide guides 200a and 200b are fitted in the grooves 194a and 194b, respectively, while facing the above-mentioned installation space SP, and extend horizontally in a horizontal state. Is provided.

On the other hand, on the rear surface of the press body 194,
As shown in FIG. 22, a cylindrical spring seat 202 for receiving the tip of the above-mentioned coil spring 198 is integrally formed. Here, this coil spring 198
Has its tip housed in the spring receiving seat 202,
As shown in FIG. 20, the rear end is engaged with the inner surface of the back cover 48 to be contracted in the axial direction, and the press body 19
4 is set so as to exert an urging force that urges 4 toward the feed roller 84.

Here, the rubber plate 196 described above is used.
In other words, when a plurality of sheets P are inserted into the first sheet insertion groove 20, they are sandwiched one by one at the rolling contact portion between the feed roller 84 and the slide press member 192, in other words, It is arranged so that a plurality of sheets P can be separated.

In the horizontal state shown in FIG. 20, the paper P inserted into the housing 12 through the first paper insertion groove 20 formed in the upper housing portion 14 passes through the first paper conveyance path F1. While passing, this slide press member 1
The feed roller 84 is pressed against the feed roller 84 by 92, and further conveyed in accordance with the rotational drive of the feed roller 84. The rubber plate 1 attached to the slide press member 192
The contact 96 is in contact with the feed roller 84 in a state of being inclined by the above-described predetermined angle with respect to the horizontal line in the horizontal state shown in FIG. As a result, the feed roller 8
The paper P that has been conveyed forward by the rotation of 4 is
The paper P is conveyed along the inclined surface of the rubber plate 196, and the front end of the paper P is obliquely provided with an under guide 184 that defines the lower surface of the common paper conveyance path F0 (more specifically, a biasing plate 190 that constitutes the under guide 184). The upper surface of) will come into contact. Therefore, the leading edge of the sheet P surely enters the common sheet transporting path F0, and then is transported in the common sheet transporting path F0.

On the other hand, when the paper P is jammed in the housing 12 while being sandwiched between the feed roller 84 and the slide press member 192, the rear end of the jammed paper P is the first paper. When protruding from the insertion groove 20, by pulling out the rear end of the rear end, the paper P can be easily taken out from the housing 12. Specifically, when the jammed paper P is to be pulled out backward, the surface of the rubber plate 196 frictionally engaged with the jammed paper P is in the moving direction of the press body 194 to which the rubber plate 196 is attached. Since they are inclined with respect to each other, a component force of the force for pulling out the jammed sheet upward is generated along the moving direction of the press body 194. This component force is applied to the coil spring 1 that presses the press body 194 against the feed roller 84.
It will function as an opposing force against the urging force of 98,
As a result, the rubber plate 196 causes the feed roller 8 to
The force that presses against 4 will be weakened. In this way, even if the press member 192 that presses the jammed paper P against the feed roller 84 is not removed, as described above, the jammed paper P is simply pulled out to remove it. It can be taken out from the housing 12.

The degree of jamming is severe, and the leading end of the jammed paper P is caught on the leading end of the press member 192,
If it cannot be pulled out backwards, back cover 4
The pressing member 192 can be pulled out backward by rotating 8 to open the installation space SP. In this way, even if the degree of jamming is great, the jam can be easily released by simply removing the press member 192 from the housing 12. Here, by removing the press member 192 from the housing 12, it is possible to easily replace the rubber play 196 as a consumable item with a new one.

Here, when the above-mentioned jam of the paper P occurs at the rolling contact portion between the platen roller 86 and the thermal line head 154, it may be necessary to release both. Therefore, as shown in FIG. 23, the release lever 46 described above is provided with the cam portion 204 at a portion where the release lever 46 faces the upper end surface of the right side plate 100 of the head support 156. As shown by the solid lines in FIGS. 1 and 23, the cam portion 204 does not contact the upper end surface of the right side plate 100 when the release lever 46 is tilted leftward in the drawings, and the pair of coil springs. The urging force of 182 allows the thermal line head 154 to come into contact with the platen roller 86 with a predetermined pressure contact force, and when the release lever 46 is tilted to the right in the figure as shown by the chain line in FIG. Contacts the upper end surface of the right side plate 100 and resists the biasing forces of the pair of coil springs 182 to move the head support 15
6, the thermal line head 154 is formed so as to be spaced downward from the platen roller 86.

In this way, during the normal printing operation, the release lever 46 is set in a state of being tilted leftward in the drawing as shown in FIG. 1, and the paper P is set on the platen as described above. Roller 86 and thermal line head 15
4 is jammed at the rolling contact portion with 4, the thermal line head 154 is separated downward from the platen roller 86 by tilting the release lever 46 to the right in the figure, and the paper P is sandwiched between the two. Thus, the jammed paper P is easily pulled out backward, and the jam is released.

As shown in FIG. 11, the feed roller 8 described above is in a state of facing the first sheet conveying path F1.
No. 4 for detecting that the paper P is inserted into the housing 12 through the first paper insertion groove 20 in a state in which it is located on the upstream side in the paper transport direction with respect to the rolling contact portion between the slide press member 192 and the slide press member 192. The first detector 206 is disposed on the rear portion 96 a of the frame body 96 that constitutes the frame 90. Further, the second guide 208 for detecting that the paper P has been inserted into the housing 12 through the second paper insertion groove 24 in the state of facing the second paper transport path F2 is the insertion guide unit 1.
It is arranged in the horizontal portion 106b of 06. Further, as shown in FIG. 20, in a state of facing the common paper feed path F0,
The platen roller 86 and the thermal line head 1 described above
A third detector 210 for detecting that the paper P is in the common paper feed path F0 in a state in which it is located on the upstream side in the paper feed direction with respect to the rolling contact portion with 54 is provided on the frame body 96 of the frame 90. It is arranged. First to third detectors 20
6, 208 and 210 are configured to be turned on when the leading edge of the sheet P passes, and turned off when the trailing edge of the sheet P passes.

Here, the first and second detectors 206, 2
Reference numeral 08 denotes a drive system 88 and a thermal line print mechanism 6
It is configured to function as a start sensor for defining the start timing of 0. In addition, the third detector 2
10 is the case where the first or second detector 206, 208 does not turn on even after a predetermined time has passed since the turn-on operation, the case where the turn-on operation continues beyond the time required for the printing operation, First or second detector 206, 208
Function as a jam sensor that detects that the paper P is jammed when the off operation does not occur even after a predetermined time has elapsed after the off operation of the thermal line printing mechanism 60.
It is configured so as to function as a cue sensor that regulates the print start timing in.

Next, the control of the printer 10 will be described with reference to the block diagram of FIG. A microcomputer (CPU) 70 that controls driving of the printer 10 is a one-chip microcomputer having an address space of 16 megabytes.
CPU (microcomputer) 70 uses address ports AB0 to AB23
And EPR via data ports DB0-DB15
It is connected to the OM 72, the DRAM 74, the first font ROM 76 and the second font ROM 78, and the G / A (gate array) 402. The CPU 70 sends out address data designating an address to the address bus AB via the address ports AB0 to AB23, and the port DB0
~ Sends and receives data from the data bus DB via DB15.

As described above, the EPROM 72 is written with a program for controlling the driving of the printer 10 and various initial data. The DRAM 74 is a dynamic area used as an area for developing a bitmap for image output based on print data transferred from the host computer or the like to the printer 10, an area for storing data from the interface, and a work area for other various processes. It's lamb. First font ROM 76 and second font R
The OM 78 stores character font data used when bitmapping the print data on the DRAM. In the printer 10 of the present embodiment, two types of fonts, Mincho typeface and Gothic typeface, can be selected, and a first font ROM 76 and a second font ROM 78 are provided corresponding to the respective fonts. (Only one is shown in the block diagram). Also, C
The PU 70, via the gate array (G / A) 402,
LED3 for exchanging data with interface (I / F) 404, power-on display, online display, font selection status display, PE (paper out) display
Processing such as driving 0, 38, 40, 42 is performed.

The interface (I / F) 404 is a printer interface (conforming to Centronics specifications) for receiving print data transferred from a host computer or the like, and has eight data lines and three control lines. is doing. The data lines PDATA1 to 8 of the interface (I / F) 404 are used for transfer of print data, and the three control lines are respectively 1) / DATASTB: a signal for reading the print data into the printer 2) BUSY: the printer 3 types of signals are transmitted: a signal indicating that data cannot be received, 3) / ACK: a signal indicating that the printer has read data.

Further, the CPU 70 is A) an online switch 410 that is turned on / off by operating the online button 32 to set whether to receive print data, and B) is turned on / off by operating the mode setting button 34 to print. Mode setting switch 412 for switching fonts, C) Forced feed switch 414 for setting forced feeding of recording paper in response to the operation of forced feed button 36, reading the ON / OFF states of each from port OL, FNT, FD. Each processing is performed according to the setting of (i.e., the operation of the online button 32, the mode setting button 34, and the forced feed button 36).

The divided voltage V_Batt of the battery voltage (or external power supply voltage) is applied to the analog port AN2. The CPU A / D-converts the voltage value applied to the port AN2 and detects the battery voltage (external power supply voltage) based on this.

The reset IC 416 detects the voltage VDD output from the DC-DC converter 450, and generates a reset signal (/ RESET) to the CPU 70 when the detected voltage falls below a certain value. The reset IC 416 sends a signal to the CPU 70 from the port / RESET (hereinafter, a port receiving a low active signal and a low active signal is indicated by "/" before a character string representing the signal or the port). Input and reset the CPU 70 unless VDD exceeds a predetermined value. Therefore, for example, when VDD becomes lower than a predetermined value during the operation of the printer 10 or when VDD does not reach the predetermined value when the printer 10 is started, the CPU 70 is reset to prevent malfunction.

The first and second detectors 206 and 208 provided at the entrances of the first and second sheet conveyance paths F1 and F2, and the common paper conveyance path F0 are conveyed through the thermal line head 154. The output signal of the third detector provided on the upstream side in the direction is input to the CPU 70 through the ports PUS, PDS and PTOP. The CPU 70 can know the sheet conveyance state by monitoring these detector output signals.

Xtal 420 is a reference clock generation circuit. Based on the reference clock generated by the Xtal 420, the transfer clock CLK for transferring the print data bit-mapped on the DRAM 74 to the thermal head side by line is output from the port Port1 of the CPU 70. That is, in synchronization with the transfer clock CLK,
The print data is transferred to the thermal head 154. The print data for one line is divided into two (DATA1 and
DATA2), Port2 and Port3 (details will be described later).

The heat generation energy of the heat generating resistor (not shown) of the thermal head 154 is the same as that of the Port 4 of the CPU 70.
~ It is controlled by the strobe signal (details will be described later) sent from Port7. In other words, the heating resistor to be driven is specified by the print data of DATA1 and DATA2, and the heating resistor is driven so as to generate the desired energy by the strobe signal applied after the transfer of the print data.

A thermistor 422 is provided to detect the temperature of the thermal head 154. Thermistor 422
The potential divided by the bleeder resistance is applied to the analog input port AN1 of the CPU 70. CPU70
Detects the temperature of the thermal head 154 by A / D converting the applied value (analog value).

The CPU 70 also sends drive control signals for controlling the drive of the motor 134 from the ports POWER_DOWN and A./A.B./B to the motor drive circuit 430. The motor drive will be described in detail later.

The port / PON is F as a switch element.
A signal for turning the ET440 on and off is transmitted. When the power switch is pushed and the main switch SWMAIN is closed, the FET 440 is turned on. Then,
Battery power is supplied via the FET 440 to a DC-DC converter 450 that converts the battery voltage for supply to the thermal head, the motor drive circuit, and the peripheral circuits. When the CPU 70 starts operating, the port / PO
N goes low, turning on FET 440. Once the FET 440 is turned on, even if the power switch is released (that is, the main switch SWMAIN is opened), the FET 440 is kept in the on state, and thus the power of the printer 10 is held. In addition, DC-D
The C converter 450 includes a CPU 70, an EPROM 72,
The battery voltage of 14.4 volts is converted to 5 volts for the driving power supply VDD of the DRAM 74, the ROM 76 and the like.
Once the signal / PON goes high and the FET 440 is turned off, no further power is supplied. Therefore, F
When the ET 440 is turned off, the power button 26 is operated again to turn on the main switch SWMAIN so that the ET 440 is restarted.

The printer 10 incorporates a nickel-cadmium battery 64 as a driving power source.
You have a voltage of 4.4 volts. Further, the printer 10 of this embodiment is provided with a power supply connector 52 so that an external power supply such as an AC adapter can be connected. The AC adapter converts 100 VAC for home use to 18 volt DC voltage, and the converted DC voltage is input to the printer 10 from the power connector 52. When the AC adapter is connected, the switching means 460 switches the power source from the built-in battery to the external power source. It should be noted that this switching is not limited to mechanical switching means operated by connecting the AC adapter to the power supply connector 52, but may be electrical switching means using a relay or the like. As an external power source, A
In addition to the C adapter, a car battery or the like may be connected via the adapter.

The thermal head 15 of the printer of this embodiment
Reference numeral 4 is a line thermal head in which 2560 dots (2560 pieces) of heating resistors are arranged in a horizontal row. 1st to 1
The data of the 280th dot (data indicating ON / OFF) is sent as DATA1, and the data of the 1281st to 2560th dots is sent as DATA2 from the CPU 70 to the thermal head 154. The dot data sent to the thermal head 154 is sent as serial data in synchronization with the transfer clock CLK.

For printing on thermal paper, 2560 heat generating resistors are divided into four groups, and each group is driven at different timings (four division drive). The four groups of heating resistors are strobe signals / STB1 to / STB4.
Is set to "L", electricity is generated and heat is generated according to the print data (dot data). It should be noted that this grouping is performed in order to prevent a large amount of current from flowing at one time and draining the battery. Therefore, when power consumption is not a problem when the battery is sufficiently charged or when an external power source is connected, two of the four groups or all four groups are driven at the same time. It is also possible to drive (that is, drive as divided into two groups).

FIG. 26 is a conceptual diagram showing the structure of the thermal line head 154. 1st to 12th as above
When the data corresponding to the heating resistors 154H up to the 80th is transferred from the CPU 70, the data is shifted register 154A provided in the thermal line head 154.
Are stored in synchronization with the transfer clock CLK. Heat generating resistor 154H and shift register 154A of the thermal head
And each bit of 154B has a one-to-one correspondence,
If the content of the shift register is "1" / STBn is "1"
When it becomes L ", the corresponding heating resistor generates heat.

When 1280 data has been sent as DATA1 (when the transfer of DATA1 is completed), / STB1
Is set to "L", and printing is started (here, the description will be made assuming four-division driving). / STB1 is from "L" to "
At the same time as "H", / STB2 is changed from "H" to "L" to continue printing, and printing based on the data stored in the shift register 154A is completed.
When it becomes L ″, DATA2 (from the 1281st to 25th) to the shift register 154B is synchronized with the transfer clock CLK.
The transfer of the 60th data) is started. And /
When printing by STB2 is completed (DATA2 transfer is already completed), / STB2 changes from "L" to "
When / STB3 becomes "H", / STB3 is set to "L" and printing is continued based on the data stored in the shift register 154B. Similarly, / STB3 becomes "H" and / STB4 becomes "L". As described above, DATA1
Upon completion of the transfer from the CPU 70 to the thermal line head 154 (shift register 154A), printing based on the data stored in the shift register 154A is immediately executed. Further, since DATA2 is transferred to the shift register 154B while the printing based on DATA1 (based on the data stored in the shift register 154A) is being performed, the printing based on the data stored in the shift register 154A ends at the same time as the shift register. 154B
Printing is started based on the stored data of.

When data is first written in the shift register 154A, the shift register 154
Although some data may be written to B,
The data is considered invalid data. Furthermore, while any strobe signal / STBn is "L", data is not written in the shift register even if the transfer clock CLK is input. Therefore,
The shift register 154A is not rewritten while DATA2 is stored in the shift register 154B. That is, when printing is performed based on DATA1, the data is shifted to the shift register 15 as DATA2.
Even if it is transferred to 4B, the contents of the shift register 154A are not rewritten. Therefore, the strobe signal /
When STB1 becomes "L", the transfer of DATA2 is started immediately in synchronization with the transfer clock CLK. This allows
As soon as printing based on DATA1 is completed, DATA2
It is possible to start printing based on. Similarly, the data DATA1 of the next row is transferred to the shift register 1 while printing is being performed by / STB3 and / STB4.
54A.

When the driving of all the heating resistors of the thermal line head 154 is completed, the printing for one line is completed. In the printer 10 of this embodiment, when the printing of one line is completed, the battery voltage is detected before printing the next line (that is, before outputting the strobe signal). If the battery voltage drops during printing, a warning is displayed. If the battery voltage falls below the minimum operating voltage, the printing operation is stopped. During printing, since a current flows through the heating resistor, the battery voltage drops by an amount that is approximately proportional to the number of pixels to be colored (the amount that is approximately proportional to the number of driven heating elements).

In the printer 10, when the printing operation is not performed (when the paper is not fed), the / POWER_DOWN signal is set to "L" to reduce the phase current of the step motor in order to reduce the power consumption. ing. Printer 10
, The phase current (specified value) when driving the motor is 200
mA, the phase current when not driving (/ POWER_DOWN signal "L") is 10mA. In order to start the printing operation, it is necessary to start the conveyance of the recording paper. Therefore, it is necessary to set the / POWER_DOWN signal to "H" and raise the phase current from 10mA to the specified value of 200mA before driving the step motor. is there. In this embodiment, the step motor is driven by the two-phase excitation method. Therefore, the current is 20mA to 400mA before the printing is started (just before the driving of the motor 134).
Increase to. Therefore, the voltage of the battery drops.
CPU70 is the battery voltage at this time (before printing / POWER_
The battery voltage at the time when ON changes from "L" to "H" is detected, and if the voltage is lower than the minimum voltage required to drive the printer 10, a warning is displayed and the printer 10 stops without performing a printing operation.

FIG. 27 is a timing chart showing the relationship between the control of the thermal head 154 and the drive motor 134 and the battery voltage.

When the bit map is expanded on the DRAM 74, one line of print data is transferred from the CPU 70 to the thermal head 154. First, DATA1 (data corresponding to the first to 1280th heating resistors) is transferred in synchronization with CLK.

When the transfer of DATA1 is completed, the motor 1
34 is started to start the conveyance of the paper, and at the same time / STB
1, / STB2 are set to "L" in order and the heating resistors (1-1
280th). / STB2 is / STB1 is "
As soon as L "changes to" H ", it changes to" L ".
When STB1 becomes "L", the contents of the shift register A cannot be rewritten even if data is written in the shift register B. Therefore, when / STB1 becomes "L", the DA is promptly changed.
The transfer of TA2 has started. That is, from the first 12
DATA2 while driving the 80th heating resistor
(Data corresponding to the 1281st to 2560th heating resistors) are transferred in synchronization with CLK. When the drive by / STB2 is completed, the transfer of DATA2 is already completed, so / STB2 is followed by / STB3, /
The STB 4 is sequentially set to "L" to drive the remaining heating resistors (1281st to 2569th heating resistors). In this way, / STB1 to / STB4 are sequentially set to "L" for a predetermined time determined by the strobe signal,
The driving of all the heating resistors in one row of the thermal line head is completed. In the figure, by setting / STB1 to "L" during the time T11 and then / STB2 to the time T21, the driving of the first to 1280th heating resistors is completed,
/ STB3 is set to "L" for time T31 and then / STB4 is set to "L" for time T41.
The driving of the heating resistors up to the first is completed. Similarly, the second line is printed at time T12, time T22, time T32, and time T42.
This is executed by setting / STB1 to / STB4 to "L" during the period.

As shown in the figure, the motor drive pulses A./A.B./B shift to the next pattern after the driving of the heating resistors by / STB1 and / STB2 is completed. That is, between T11 and T21, A = "H", / A = "L", B = "L",
The pattern is / B = "H", and the pattern between A31 and T41 is A = "H", / A = "L", B = "H", / B = "L". After that, 2 of the heating resistors divided into 4 in the same manner
Each time one is driven, the excitation pattern is updated. In this printer, when one pulse (one pattern) of drive pulse is applied to the drive motor 134, the paper advances by ½ line. That is, when the drive pulse of 2 pulses is applied to the drive motor 134, the paper is conveyed by one line, and all the heating resistors are driven during that time. In this way, the paper is conveyed for one line, and
By repeating the process of printing lines, 1
Printing of pages is completed.

By the way, the printer 10 uses the nickel-cadmium battery 64 as the power supply voltage. Nickel-cadmium battery 64 is a new battery (immediately after full charge)
Has a characteristic that the voltage is high and the voltage gradually decreases as it is consumed. Moreover, although the voltage decreases relatively slowly with time at the beginning, after the voltage decreases to a certain degree, the voltage decreases sharply thereafter, and the printer 10 cannot print. Therefore, in the printer 10, the battery voltage is detected every time one line is printed, and when the detected battery voltage becomes lower than a predetermined value, a warning is displayed and when it becomes lower than the minimum operating voltage. The printing operation is stopped.

Although the motor drive is started from Tb, as described above, the / POWER_DOWN signal is changed from "L" to "H" before applying the drive pulse (Ta). The motor is driven by the two-phase excitation method, and after the start of driving (Tb),
Any two of A ・ / A ・ B ・ / B are "H" and two are "H"
The pattern "L" is formed. Therefore, it is considered that there is almost no change in the drive current due to the motor drive during motor drive. In the figure, Ta is / POWER_D above.
The battery voltage is decreasing due to a change in OWN. At Tb, the battery voltage is further decreasing due to the start of driving the motor. The change (increase) in the battery voltage between Tc and Td is that the battery voltage is increasing because the printing rate (the number of driving heating resistors) is less than the number of heating resistors that generate heat between Tb and Tc. Is.

The battery voltage is detected by the T
at a, Tb, Td. What is performed at Ta is the voltage detection at the time of increasing the phase current of the motor as described above, and thereafter, the voltage detection is performed for each line during printing.

FIG. 28 is a flow chart for explaining the operation of the thermal printer of this embodiment. When the power is turned on, an initialization memory test is performed (S1
~ S5). As described above, when an error is found in the DRAM 74 (Y: S7), the printing operation is not performed, the error display is performed (S9), and the operation is stopped. First in S11
If the detector 206 or the second detector 208 detects the sheet, the sheet is cueed (conveyed to the print position) in S13. The processing of S11 to S15 is repeated until data arrives at the interface I / F. Note that the cueing of the sheet in S13 is to convey the sheet to a predetermined print position only when the sheet is detected for the first time, and once the cueing is performed, the subsequent steps in this step (S13) are performed. Is not performed, and the process proceeds to the next S15.

When data arrives at the interface I / F (Y: S15), the presence of paper is checked again (S1).
7). If a sheet is detected here, a cueing process is performed (S19). Similar to S13, the cueing process of S19 conveys the sheet to the print position only when the sheet is detected for the first time. If the sheet has already been conveyed to the predetermined position by the cueing process, Do nothing and proceed to the next step.

Next, based on the received data, the DRAM
The image is written in 74 (S21). The processes of S15 to S21 are repeated until the image for one page is written. When image writing is completed (Y: S2
2), paper detection is performed in S23. Here, the process does not proceed unless the paper is conveyed to the print position (S
23, S24). In the cueing process in S24, the paper conveying process is performed only when the paper is detected for the first time, like the cueing process in S13 and S19 described above.

When the image is written and the paper is conveyed to the print position, the CPU 70 starts sending DATA1 (S25). When the sending of DATA1 is completed (S25), the driving of the drive motor 134 is started (S2).
7) Then, shift to printing processing. The printing process starts from S28. First, in S28, the number of print dots (that is, the number of driven heating resistors) n is obtained. Next, in S29, the energization time (driving time) t is obtained by the equation t = A · n / N (1) Here, t is the energization time, A is a constant determined by the configuration and drive voltage of the thermal head, n is the number of heating resistors to be driven, and N is the total number of heating resistors (n = for the printer of this embodiment). 2560). The energization time calculated here is the strobe signal / STBn (n = 1 to 1
It is a time interval in which 4) is set to "L". Printing is performed according to the energization time calculated here (S30). After the printing operation, the voltage drop is checked in S31. If the battery voltage is below a predetermined value (12 volts or below) (Y: S3
1) A warning is displayed (S33), and if it is below the minimum operating voltage, the printing operation is stopped (S35). S28 ~ S3
When printing of one page is completed in the loop of 7 (Y: S3
7) Then, the printed sheet is discharged (S39), and the next sheet is introduced and the bitmap is developed.

Although the above equation (1) is set so that the energization time t is substantially proportional to n, the equation t = T + A may be set according to the configuration of the thermal head, the characteristics of the heating resistor, the characteristics of the power source, etc.・ N / N ・ ・ ・ ・ (2) may be used. Here, T is a constant. Alternatively, it goes without saying that not only the linear expression of n but also an expression that gives a more preferable result can be set according to the conditions.

In the above embodiment, the thermal line printer in which the heat generating resistors are arranged in a line and the thermal paper is used as the recording paper has been described. However, it is a printer for printing on the recording paper by using thermal energy. For example, the present invention can be applied to any printer.

[0094]

As described above, in the thermal printer according to the present invention, the heat generating resistors are arranged according to the number of driven resistors among the heat generating resistors arranged in the thermal head (that is, according to the printing rate). Since the drive energy (energization time) of the body is controlled, it is possible to print with a uniform print density regardless of the print rate.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an embodiment of a thermal line printer to which a printer according to the present invention is applied in a horizontal position.

FIG. 2 is a perspective view showing a configuration of an embodiment of a thermal line printer to which the printer according to the present invention is applied in a vertically installed state.

FIG. 3 is a transverse cross-sectional view showing the internal structure of the housing 12 with the battery lid 18 removed and the upper housing portion 14 removed from the thermal line printer shown in FIGS. 1 and 2.

FIG. 4 is a vertical cross-sectional view showing a cross-sectional shape of the thermal line printer taken along the line AA in FIG.

FIG. 5 is a top view showing how the control board is attached.

FIG. 6 is a plan view showing an upper surface shape of a frame.

FIG. 7 is a left side view showing the left side shape of the frame.

FIG. 8 is a right side view showing a right side shape of the frame.

9 is a vertical cross-sectional view showing the cross-sectional shape of the frame taken along the line BB in FIG.

10 is a vertical cross-sectional view showing a cross-sectional shape of the frame taken along the line CC in FIG.

11 is a vertical cross-sectional view showing a cross-sectional shape of the thermal line printer taken along the line D-D in FIG.

FIG. 12 is a perspective view showing a positioning state of the platen roller and the head support taken out from each other.

FIG. 13 is a perspective view showing the configuration of a feed roller.

FIG. 14 is a left side view of a frame showing a gear train that constitutes a drive system.

FIG. 15 is a right side view showing a fitted state of the head support with respect to a bearing that pivotally supports the other end of the platen roller.

FIG. 16 is a left side view showing a fitted state of a head support with respect to a bearing that axially supports one end of a platen roller.

FIG. 17 is a vertical cross-sectional view of the thermal line printer showing the arrangement of coil springs.

FIG. 18 is a bottom view showing a state in which a lower housing portion, a control board, and a head support are removed from the thermal line printer to show an arrangement state of an under guide.

FIG. 19 is a vertical cross-sectional view of the thermal line printer showing a biasing state of the biasing plate of the under guide.

20 is a vertical cross-sectional view showing a cross-sectional shape of the thermal line printer taken along the line EE in FIG.

FIG. 21 is a perspective view showing the slide press member taken out from the front side.

FIG. 22 is a perspective view showing the slide press member taken out from the back side.

FIG. 23 is a vertical cross-sectional view for explaining the release operation by the release lever.

FIG. 24 is a rear view showing a state in which a rear surface of the housing is removed to show a disposition state of the slide press member.

FIG. 25 is a block diagram illustrating a control unit of a printer according to the present invention.

FIG. 26 is a conceptual diagram illustrating the structure of the thermal head of the printer according to the present invention.

FIG. 27 is a timing chart illustrating print control of the printer according to the present invention.

FIG. 28 is a flowchart illustrating print control of the printer according to the present invention.

[Explanation of symbols]

 P Paper F0 Common paper conveyance path F1 First paper conveyance path F2 Second paper conveyance path Fd Paper ejection path 10 Thermal line printer (printer) 20 First paper insertion groove 22 Paper ejection groove 24 Second paper insertion groove 26 Power Button 28 Power Switch 30 Power (POW / CHRG) Lamp 32 Online (ONLINE) Button 34 Mode Setting (MODE) Button 36 Forced Feed (FEED) Button 38 Online (ONLINE) Lamp 40 Font (Gothic) Lamp 42 Paperless Display (PE) Lamp 50 Connector 52 Power Connector 64 Nickel-Cadmium Battery 70 Microcomputer 72 EPROM 74 DRAM 76 First Font ROM 78 Second Font ROM 206 First Detector 208 Second Detector 210 Second 3 detectors

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuka Suzuki 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Kogaku Co., Ltd. (72) Inventor Minoru 2-36 Maenocho, Itabashi-ku, Tokyo No. 9 Asahi Kogaku Industry Co., Ltd.

Claims (3)

[Claims] 1. A plurality of heating resistors, a driving unit that drives the plurality of heating resistors, a detection unit that detects the number of the plurality of heating resistors that are driven for printing, and the detection unit. A control means for controlling the drive means so as to change the energy generated when each of the plurality of heating resistors is driven, based on the detection result of 1. 2. The driving means has a voltage applying means for driving by applying a predetermined voltage to the plurality of heating resistors, and the control means sets a time interval at which the voltage applying means applies a voltage. The thermal printer according to claim 1, further comprising a time changing means for changing the time. 3. The thermal printer according to claim 2, wherein the time changing unit sets the time interval so as to be substantially proportional to the number of driven heating resistors.